<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript" src="js/jQuery.js">
			
		</script>
	</head>
	<body>
		<div id="d1" style="background: red; width: 300px;height: 300px;opacity: 0;">
			
		</div>
		<input type="button" name="btn" id="btn" value="显示" />
	</body>
	<script type="text/javascript">
		$(function(){
			$('#btn').toggle(function(){
				$('#d1').stop().animate({opacity:1},2000);
			},function(){
				$('#d1').stop().animate({opacity:0},2000);
			});
		})
		console.log(Math.floor(0.1+0.2)!=0.3);
	</script>
</html>
